Hair transplantation is a surgical technique that involves moving skin containing hair follicles from one part of the body (the donor site) to bald or balding parts (the recipient site).
Hair naturally grows in follicles that contain groupings of 1 to 4 hairs, and transplant techniques typically move the 1-4 hair “follicular units” from the donor site to the recipient site. Hair follicles grow at an angle to the skin, pointing from anterior to posterior.
The follicles of hair are typically removed from the donor site using punches of between 0.7 mm and 1.25 mm in diameter. The punches are tubular bodies having a skin-contacting cutting edge, and are typically mounted in a tool that causes the punch to rotate as the punch is brought into contact with the donor site. Hair follicles are very easily damage during the removal process, and damaged follicles are unlikely to be successfully transplanted.
Curled follicles are extremely susceptible to damage by follicle punches and are therefore particularly difficult to extract for successful transplantation. Such follicles are curled beneath the skin and are easily cut and/or damaged by the advancing cutting edge of conventional punches as the punch penetrates the donor site's tissue.